The method of finite elements is in certain cases advantageous when dealing with flow problems in a finite domain. This is particularly so when attempting to include subcritical compressibility effects.In the present note we first consider the two-dimensional flow using TRIC and TRIM-like triangular elements in conjunction with the concept of the stream function, which is assigned to the nodal points of the elements. The application of the stream function allows a direct and exact satisfaction of the boundary conditions. Strictly the elements in question could also be used in conjunction with the potential function but the observance of the boundary conditions is then cumbersome.